Key terms/topics: the nature of abstraction; different views about abstraction among Aristotle’s commentators; the view of Aquinas, as well as of all other Latin philosophers on abstraction; Averroes’ view on Aristotelian abstraction; Jean of Jandun’s views on abstraction; Zabarella’s own reading; the respective roles of the agent and patient intellects in carrying out abstraction; whether abstraction is something carried out by the agent or patient intellect.

The following is worthy of consideration: how abstraction occurs, whether by means of the passive intellect or by the agent; for, by knowing this, the full, proper activity of the agent intellect will be known.

The Opinion of the Latin Commentators and of Averroes

The opinion of many is that abstraction arises by means of the agent intellect, for many of the Latins authors say this and Averroes too openly asserts it in Commentary 18, Book III of the De Anima, and at the end of 20 where he says that Aristotle was compelled to suppose the agent intellect for the sake of abstraction, since its activity is abstraction, for, it abstracts the universal from images and strips it bare of all material conditions.

Therefore, the passive intellect’s act of understanding is nothing more than a reception of this universal as it is abstracted from the agent. Furthermore, the action of the agent itself is nothing more than the abstraction of universals from all material conditions so that it may move the passive intellect. Therefore, for Averroes (which is the standard reading of his text), abstraction is making of what is potentially understood, actually understood, so that abstraction is the work of the agent alone.

Averroes’ Use of Alexander

Averroes, in addition, cites a remark attributed to Alexander of Aphrodisias’ we may find in Book II of his De Anima, in the chapter on the agent intellect. There Alexander says that it is not only necessary that each of the two powers is in the intellect, one for acting, the other for undergoing change, but it would be even better to explain the nature as “acting” than as “undergoing.” When he writes on these lines, Averroes says that the intellect does not differ from sense concerning its passivity, but only with regard to its activity, since a sensory agent is not given, but an agent intellect is, which makes things intelligible, which is called “abstraction.”

Jean of Jandun

This opinion should not be admitted, and is efficaciously opposed by Jean of Jandun, although he himself applies it to another proof. He wishes to prove that the agent intellect does not act upon images, and contributes nothing to them. He argues as follows: if the agent intellect illuminates images, it illuminates everything existing in it’s light equally, and equally makes all things intelligible; nor is it capable of adding a single thing to them, but by its light, it can separate and act so that one thing is understood without the other. In the same way, light, shining upon a picture makes all its colors equally visible , equally illuminates everything; however, it does not act upon it in such a way that it contributes anything to the images and in no way works upon them.

Refutation

But the consequent is, in very truth, invalid and Jean commits the fallacy, “from the qualified case to the unqualified statement,” because the argument certainly proves that the agent intellect does not separate or abstract one thing from another, since it illuminates the whole image equally, and everything within it. Accordingly, it is most valid and efficacious for proving that the agent intellect cannot bring about abstraction, since abstraction is nothing other than the separation of one thing from another, and the reception of one thing while not receiving another. But it does not prove that the agent intellect does not in any way at all engage itself with images. It acts upon them, necessarily, as a step toward abstraction, though it does not enact abstraction itself, as we shall soon make clear:

Two Things Should be Considered in Abstraction

for, whenever we wish to abstract one thing from others, and to grasp it while leaving the others behind, it is certain that we must hold one thing distinct from the others, since if they are confused and mixed together, we are able to accomplish very little thereby. For example, if water were offered to us mixed with wine, there is no faculty in us for receiving the wine without also receiving the water-which is what is meant by “abstraction.” But if someone were to separate wine from water by some device, so that each one could be examined distinctly, it would be easy for us to receive the remaining one.

Two acts must therefore be considered: (1) the act of distinguishing one thing from another; (2) the act of receiving one thing, while others are omitted. But these two acts cannot pertain to the same intellect: rather, one belongs to the agent, the other to the patient, since, if to abstract is to receive one thing while others are left behind, it is certain that it is not the work of the agent intellect, but of the patient. For the patient apprehends the quiddity of a thing shining forth in the image and receives it without its material conditions and without other potential apprehensions that are in the image, and thus it is said to abstract.

However, it is not able to act unless everything in the image appears clearly beforehand, which clarification is the work of the agent intellect. For, it illuminates equally all phantasms that come into its light and acts so that everything appears distinctly. For example, it acts upon the image of a horse, so that the nature of body appears distinctly, as well as the nature of a living thing, the nature of an animal, the nature of a horse, and of quantity, quality, and so on for other accidents, since all these were in the phantasm in a confused state and had been indistinct. But being illuminated by the agent, they are presented to the passive intellect, clear and distinct, so that considering all these it may itself conteplate what it wishes, whether the confused whole or a single quiddity shining forth in it, having also omitted others to understand it.

The same thing occurs in the case of colors: for, when light shines weakly in the air, we see the total picture in a confused state, but do not see its colors with any clarity. However, with the appearance of the sunlight, all colors appear distinctly and all the finest lineaments, and we are free and ready to gaze upon whatever we wish in the picture, having disregarded the others: for, at first place we consider the confused whole, but afterward turn our attention to the individual particulars and focus sometimes focus our attention upon one particular thing while disregarding that and sometimes regard the latter without considering the former.

Vision itself does this, not light, if indeed light only illustrates and makes clear; however, vision considers this part without that, and that without this. But the philosopher does not call this abstraction, since, in order that it may be called abstraction, properly speaking, it is not sufficient that one thing be received without the others, but it is also necessary that it be transferred from one order of being into another-which does not happen in the case of vision. For the eye, when it receives this thing to be seen without apart from others, does not, in order to accomplish it, bring it to another order of discernability, since all things are sensible therein, the whole as much as the parts.

But when the intellect abstracts, it transfers a thing from one order of being into another–or rather, it presupposes that such a translation has been carried out. Moreover, this translation is, in truth, carried out by the agent, that, when it illuminates, makes a sensible thing intelligible, whereupon it is then received by the passive intellect, and thus is said to abstract. Therefore, in this way the agent intellect is said to differ from light, since light does not transfer colors to another grade of intelligibility, whereas the agent intellect makes the intelligible out of the sensible.

The error of Jean of Jandun is also clear from these considerations, then, who concluded from this that the agent intellect contributes nothing to phantasms, since he, in fact, atrributes the idea of a distinguishing light to Aristotle; however, the agent intellect makes no selection of object. This is accomplished by the patient intellect, and is called abstraction in a formal sense, because the action of the agent intellect is not abstraction, except antecedently, since, of necessity, it precedes abstraction.